Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
  • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
  • C23C22/07—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing phosphates
  • C23C22/08—Orthophosphates
  • C23C22/12—Orthophosphates containing zinc cations
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
  • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
  • C23C22/07—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing phosphates
  • C23C22/08—Orthophosphates
  • C23C22/12—Orthophosphates containing zinc cations
  • C23C22/17—Orthophosphates containing zinc cations containing also organic acids
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
  • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
  • C23C22/34—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides
  • C23C22/36—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates
  • C23C22/362—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates containing also zinc cations

Definitions

• the invention relates to a process for the phosphating of metals, in particular iron, steel and galvanized steel, with aqueous, acidic baths which contain zinc phosphate and, if desired, customary activating and / or layering-improving additives.
• the new process is particularly suitable as a pretreatment of the metal surfaces for a subsequent cathodic electrodeposition.
• the Laid-open European Patent Application 0056881 aims to achieve an improvement in that the temperature range of 30 - 60 ° C is carried inkphosphattreateden with chlorate Z, the O 5 - 1.5 g / 1 Zn, 0.4 - 1.3 g / 1 Ni, 10 - 26 g / l P 2 O 5 and 0.8 - 5 g / l ClO 3 , to which no nitrite is added and in which the weight ratio of Zn: Ni to a value between 1: (0.5 - 1.5), Zn: P 2 O 5 to a value between 1: (8 - 85) and free P 2 O 5 : total P 2 O 5 to a value between (0.005 (at approx.
• the invention is based on the object of proposing acidic, aqueous zinc phosphate-containing baths within the scope of the knowledge known per se for phosphating metal surfaces, which baths work in particular with a significantly lower total acid content.
• the production of high-quality zinc phosphate layers should be ensured, which are characterized in particular by comparatively high iron contents and are accordingly very particularly suitable for a subsequent cathodic electrocoating.
• the invention aims to enable a type of process that can be operated effectively at very low temperatures.
• the solution of the task according to the invention is based on the finding that the combination of certain bath parameters enables the effective reduction of the total acid content and thus the desired reduction in the chemical requirement, but that at the same time these baths at temperatures below 40 ° C effectively contain the desired iron Zinc phosphate layers can be deposited.
• the invention relates in a first embodiment to a process for phosphating metal surfaces, in particular iron, steel and galvanized steel, by treating them with aqueous, acidic zinc phosphate baths at only moderately elevated temperatures.
• the new method is characterized in that one works in the temperature range of 22-38 ° C with phosphating baths which correspond to the following conditions: 2-6 g / 1 zinc, 4-23 g / 1 PO 4 3- , free acid content 0.05 0.4 points and bath pH 3.0 - 4.0.
• the method according to the invention thus uses comparatively high levels of zinc in the bath solution, in particular in comparison with the cited prior art documents, but at the same time only limited amounts of phosphate ions - and ultimately only limited amounts of total acid - are used. It is preferred to work with baths in which the ratio Zn / PO 4 3- is in the range from 1: 2 to at most 1:11, preferably at most up to 1:10.5 or 10.
• the invention opens up the possibility of using baths in which this ratio of Zn / PO 4 3- lies clearly within the lower values of the specified maximum working range.
• ratios Zn / PO 4 3- in the range from 1: 2 to 1: 8 and in particular in the range from 1: 2 to 1: 4 can be used.
• This PO 4 3 content of the bath this means in absolute terms that it is possible to work with comparatively low concentrations of the PO 4 3 value.
• This PO 4 3 content is preferably in the range from about 4 to 15 g / 1 bath solution, preferably up to a maximum of 13 g / 1 bath solution. According to the invention, it is particularly expedient to work with a PO 4 3 content in the range of about 4-8 g / 1 bath solution.
• the zinc content in the phosphating bath is in the range of 2-4 g / l bath solution.
• the preferred free acid content is in the range of 0.1-0.2 points.
• the preferred pH range for these phosphating baths of the invention is in the range of about 3.5-4.0. With baths of this kind work effectively in the temperature range of 28 - 38 ° C.
• phosphating baths whose total acid content does not exceed numerically limited values in the range of about 30 points.
• Particularly suitable for the process according to the invention are phosphating baths with a total acid content in the range from 8 to 30 points, preferably in the range from about 9 to 15 points.
• auxiliary components or constituents customary in baths of this type can also be used in the phosphating solutions according to the invention. It is of particular importance here, however, that the common use of manganese to this day is not necessary. This is an important advantage of the method according to the invention over other characteristic baths of the prior art, in particular over the so-called low-zinc baths which operate at a comparatively higher temperature.
• the layer formation on the metal surfaces can be improved by adding simple and / or complex fluorides.
• the fluoride ion content is expediently in the range of 0.01-2 g / l bath solution.
• the complex fluoride can be, for example, the SiF 6 2- ion, concentration ranges of about 0.01-2 g / l bath solution also being preferred.
• the solutions can also contain complexing agents known per se of organic or inorganic origin.
• Suitable organic complexing agents are, for example, tartaric acid or tartrate, hydroxyethylene-diamino-triacetic acid or its salts, gluconic acid or its salts and / or citric acid or its salts.
• Inorganic complexing agents are polyphosphates, for example tripolyphosphate. or hexamethaphosphate. Complexing agents of this type are usually present in the bath in quantities of 0.01-5 g / l.
• the treatment bath can contain further metal cations, in particular divalent metal cations.
• the co-use of nickel (I I) may - be in the phosphating.
• the nickel content is limited in relation to the zinc and at most reaches this zinc content.
• the Zn / Ni ratio of about 1 / 0.5 is preferably not exceeded.
• Preferred nickel contents can be within the teaching of the invention in the range of about 0, 01-1 g / 1 B are adinate.
• Zinc phosphate layers with a high iron content designed according to the invention are suitable for all types of application of phosphate layers known to date, but they have particular advantages for a subsequent cathodic electrocoating. They show a high resistance of the paint film against paint infiltration under corrosive stress as well as high and satisfactory values of the paint adhesion to the metallic surface.
• the method according to the invention is therefore used in practice, for example in the phosphating of car bodies.
• This concentrate was diluted to give a solution with 0.18% Zn, 0.002% Ni, 0.96% PO 4 , 0.17% NO 3 , 0.004% tartrate and O, 15% ClO 3 , which was a Monchure- P has unktress of 9.8.
• the free acid was reduced to a pH in the range 3.5-4 by adding sodium hydroxide.
• the parts were then rinsed with water, rinsed with distilled water and dried by blowing with compressed air.
• the parts were then coated with a cathodic electrocoating material and dried by heating at 185 ° C. for 20 minutes.
• the dry film thickness of the paint was 18 pm.
• the parts were then provided with individual cuts and subjected to the salt spray test DIN 50021 for 240 hours.
• the evaluation according to DIN 53167 showed an infiltration of ⁇ 0.1 mm. It follows that the proposed method of working gives a good coating despite the low treatment temperature.
• This concentrate was diluted to give a solution with 0.48% Zn, 1.68% PO 4 , 0.19% NO 3 , 0.19% ClO 3 and 0.024% gluconate, which had a total acid score of 25, 5 has.
• the free acid was reduced to a pH in the range 3.5-4 by adding sodium hydroxide. Then 0.1 gl NaN0 2 were added to the solution.
• the dry film thickness of the paint was 18 ⁇ m.
• the parts were then provided with individual cuts and subjected to the salt spray test DIN 50021 for 240 hours.
• the evaluation according to DIN 53167 showed an infiltration of ⁇ 0.1 mm. It follows that the proposed method of working gives a good coating despite the low treatment temperature.
• This concentrate was diluted to yield a solution having 0.34% Zn, 0.85% PO 4, 0.34% NO 3, 0.27% ClO 3, 0, 007% Si F 6 0.007% and 0.014% F
• 3-nitrobenzenesulfonic acid which has a total acid score of 14.4.
• the free acid was reduced to a pH in the range 3.5-4 by adding sodium hydroxide.
• the dry film thickness of the paint was 18 ⁇ m.
• the parts were then provided with individual cuts and subjected to the salt spray test DIN 50021 for 240 hours.
• the evaluation according to DIN 53167 showed an infiltration of ⁇ 0.1 mm. It follows that the proposed method of working gives a good coating despite the low treatment temperature.

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• Chemical & Material Sciences (AREA)
• Metallurgy (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Treatment Of Metals (AREA)
• Secondary Cells (AREA)
• Glass Compositions (AREA)
• Laminated Bodies (AREA)
• Inorganic Compounds Of Heavy Metals (AREA)
• Chemically Coating (AREA)
• Saccharide Compounds (AREA)

Priority Applications (1)

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Publications (2)

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Family Applications (1)

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Cited By (1)

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Citations (5)

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• 1982
  • 1982-12-03 DE DE19823244715 patent/DE3244715A1/de not_active Withdrawn
• 1983
  • 1983-11-22 GR GR73035A patent/GR81290B/el unknown
  • 1983-11-25 DE DE8383111813T patent/DE3371999D1/de not_active Expired
  • 1983-11-25 EP EP83111813A patent/EP0111223B1/fr not_active Expired
  • 1983-11-25 AT AT83111813T patent/ATE27715T1/de not_active IP Right Cessation
  • 1983-11-28 CA CA000442079A patent/CA1205726A/fr not_active Expired
  • 1983-11-30 US US06/556,746 patent/US4490185A/en not_active Expired - Fee Related
  • 1983-11-30 TR TR10000/83A patent/TR23183A/xx unknown
  • 1983-12-02 AU AU21920/83A patent/AU561955B2/en not_active Ceased
  • 1983-12-02 ES ES527732A patent/ES527732A0/es active Granted
  • 1983-12-02 ZA ZA839008A patent/ZA839008B/xx unknown
  • 1983-12-03 JP JP58229026A patent/JPS59110785A/ja active Pending

Patent Citations (5)

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